I had a boss once who would say "the last 10 percent is 50 percent of the work", and that seems true here. I picked up this 1981 with a bottom end noise from a friend, and put in a low-mile Vortec. I had to learn about intake manifolds and find one for the Vortec heads, and get a new throttle/trans cable bracket to fit the intake. I put in an in-tank electric fuel pump, because the Vortec can't use a mechanical fuel pump. I added a fuel pressure regulator, and a controller for the pump. I also replaced seals and gaskets on the trans because it was leaking, and did new radiator hoses, plugs, motor mounts, water pump gaskets, timing cover, and probably some other wear items. The only thing I forgot to do was replace the pinion seal on the diff, and now that everything is back together I see that I'll probably have to remove the rear axle to do that.

I thought it was done, but I've been fighting with the carb for weeks now. It's a Holley 1810, which I have no experience with. I've always avoided carbs in favor of fuel injections, and have sworn several times that I'd never own another carburetor. But here I am. I put on an electric choke, since it had a manual choke with no cable, but it's still not right. If I push the choke plate(?) closed, the car will run cold, but the choke won't close by itself. I've got a buddy coming by today who knows about these things, so I'm hopeful that we might get to drive it.

I did notice a pretty good leak from the power steering pump. I can't spot exactly where it's coming from, so I'm thinking I'll get a rebuild kit and see if that seals it all up. I also see a leak at the bottom of the radiator outlet, so hopefully I can braze that with the radiator in place. The radiator has greenish corrosion in a number of places, so it might have to be swapped out. I think with those things fixed it might be driveable long-term. Although I'm in south Florida so I'll need AC in a couple months. The system has pressure and what looks like a rebuilt compressor, but for some reason the clutch connector is unplugged. I haven't investigated further.

Here's hoping it runs soon.

 

If you have the stock power steering system, there's a good chance your leak is from the control valve or the ram, it's pretty common. -- Unless you're sure its from the pump.

 

It is the stock power steering system. The drips are falling off the bottom of the pump reservoir, but I can't tell exactly where they are from. The previous owner put on new hoses, and I tightened them, but that didn't help. I had to google what the control valve is, but I'll take a closer look at that before I tear into the pump. It wasn't much fun getting the pump off when I was pulling the old engine, but at least everything is clean now.

 

Looks like the control valve and the ram are new, along with the hoses. The pump is most definitely not new, so I'll do the rebuild.

1981 Corvette power steering control valve

1981 Corvette power steering ram

1981 Corvette power steering pump

 

So my buddy came over tonight, and did his magic on the carburetor and timing, and it is running pretty well. And he set it up so it doesn't stall when you drop it in gear. I think the choke is correct also, but will confirm that in the morning when it's cold.

But in the "last 10 percent is 50 percent of the work" category I now have a fuel leak in the rear by the tank. It's not entirely unexpected, since I put in a 50 psi in-tank pump and left the 40-year-old hoses unchanged. They run from the top of the tank to the hard lines on top of the rails. Maybe I can twist around in there and change them, but I feel like I might have to drop the tank.

I also have the power steering leak I mentioned in the last post, so I'll rebuild the pump. And I'm not positive that the coolant leak is coming from the radiator, but I'm pretty sure of it. The fins on the radiator are so corroded in some places that they crumble when I touch them. So I think I have a new radiator in my future.

At least the headlights work. It was the first time I tried them. Wait, I didn't try the high beams.

 

I replaced the fuel hoses on top of the tank yesterday. That was a lot of work for two 3" pieces of hose. It took longer because when I removed the tank I didn't pay attention to what angle it sits. It would be much easier if I had to do it again. Also I think I could have just dropped the tank a few inches and had enough access to replace the hoses. But while it was out I re-glued the foam cushion that goes on top of the tank to the body. Also I removed the circular plastic piece for the spare tire (anybody want it?) because there is no spare tire and some of the spare-related other pieces are missing. I painted the tank support and straps since you can see them now.

And I found the build sheet on top of the tank, but it was half gone and completely illegible.

I removed two unused exhaust hangers, since there are side pipes. I also removed two brackets that look like they might have had something to do with the exhaust; does anybody know what those are? And I'd also like to remove the bracket that holds the bolt for the spare tire -- does that serve any other purpose like adding rigidity to the cross member that it's on? Or can I remove it?

PS pump rebuild kit should be here soon, so that's next on the list. And then assess the coolant leak. And then maybe I can drive it.


gas tank out and on the bench

the build sheet was mostly gone. when I brushed of the dirt it was almost unreadable.

can I remove this bracket for the missing spare tire?

gas tank back in place, with support member and straps painted.

I removed these brackets which might have had something to do with the exhaust.

 

I know this one!

These are to prevent the rear bumper from being damaged when the car is towed by an old-school strap-style tow truck. I used them to mount my backup lights when I went to a 68-style taillight configuration.

https://www.corvetteforum.com/forums...-brackets.html

 

I would never have guessed what those parts are.

I did the power steering pump rebuild yesterday. It was my first time doing one, and it went pretty smoothly. The pics and info at this website were very helpful: https://www.corvette-restoration.com...g-pump-rebuild It was pretty much just replacing seals and o-rings. I had to rent a pulley puller/remover at the auto parts store. I put it back in today, and after idling for 10 minutes I didn't see any leaks, so maybe it's fixed. Tomorrow I'm going to try to drive around the neighborhood. There's still the radiator leak to deal with, but it seems to be a slow leak.

 

First drive around the block today! I almost didn't go, because the engine kept stalling in my driveway, and there's lots of traffic in the neighborhood It felt like it was starved for fuel, so I checked the status light on the fuel pump controller, and sure enough it was out. I cycled the ignition a few times, and it came back on. I already don't trust the controller because it's supposed to cut off if it doesn't see a signal from the tach, but it just runs the fuel pump when the ignition is on, regardless of whether the engine is running. I had added the suggested diode, but that didn't fix it. I think I will replace the controller with a relay and an oil pressure switch.

The test drive went well, with no stalls, and no scrapes on the speed bumps. I even chirped the tires twice while learning to modulate the accelerator pedal right. And no leaks at all from the power steering. But in a 2000' drive I found the following issues:

- emergency brake does nothing, and now i remember I need to adjust it after disconnecting it during the engine replacement
- driver side sun visor keeps falling down -- super annoying, but I don't see a way to adjust it
- turn signal indicators on dash don't work, and turn signals flash fast on both sides -- all bulbs are good
- no dash lights
- horn doesn't work -- maybe clock spring? I'll get out my Power Probe

So all of those things, plus the fuel pump controller, plus I just don't trust the radiator. The temp stayed below 200, but there is seepage, and the radiator is old and has lots of blue-green corrosion. I've read the sticky thread about radiators, but I'm an Amazon warrior, and I can get an aluminum 3 row radiator with shroud and two fans and relay for $233. I'll see if it's too good to be true. Plus it will be nice to get the mechanical fan and fan shroud out of there and make some space in front of the engine.

That should fix all of the issues except the AC vents not working (and whatever AC issues there are after that), and the pinion seal leaking. I think those can wait. Hopefully the next test drive will be a little longer.

 

I figured I'd do a quick adjustment on the emergency brake cable. Nope! It's already maxed out. I tried turning the rear wheels, and it was very difficult. So I pulled off the left rear rotor to take a look. It has a new rotor, pads and parking brake shoes. I can't tell whether the caliper is new, but there is seepage and crystallized brake fluid around the pistons. I pretended I didn't see it, but when I tried to push the pistons back into the caliper, they would pop back out after I pushed them in! I've never seen that before. Yes, I had the top off the reservoir. I figured maybe the brake hose had swollen shut and was holding pressure, so I opened the bleeder. And the bleeder was plugged up. Even when I completely removed the bleeder and had fluid coming out, but couldn't push the pistons in.

At that point I gave up, and ordered a rebuild kit and hose for the left rear. I started to get brake cables, but then I read about what's involved in replacing the front (disassemble the console), and to do the rear cable I'd have to pull the right rear brakes apart, and I'd probably find the same situation as the left. I did read that I can fabricate a spacer for the cable to take up some slack, so I'll try that. That job got a whole lot bigger than I expected.

I was able to convince Amazon to accept the fuel pump controller as a return, even though I'm past the return period. And confession time -- it wasn't the Revolution Electronics controller, I bought the cheap Chinese knockoff instead. I know. So I ordered the genuine Revolution controller, and hopefully that fixes my fueling issues. I also have the radiator and fans coming by the weekend. And I looked briefly for the turn signal flasher under the passenger side dashboard, but couldn't find it.

 

Not sure if it will help, but I actually backed off the parking brake y-cable adjustment, then kept taking off the rotor and adjusting the brake shoe adjustment until I could just barely get the rotor back on over the shoes. Then I adjusted the y-cable again and I had good results at about halfway thru the adjusting threads. Good enough to hold the car on an incline.
Oh, and it’s not an emergency brake, even in tip top condition. Ain’t no way that thing is stopping a rolling car. Lol

 

There is a procedure to adjust the parking brakes in the shop manual. It took me three tries to get it mechanically correct, due to some imprecise stainless parts, but once I did, the procedure worked.

If your parking brake will keep a stopped car from moving when shifted from N to D, that's probably the best you can hope for.

 

I replaced all the seals in the left rear caliper, and it is no longer weeping fluid. I did not know there are springs behind the pistons, which is why I thought the caliper was holding pressure. I read the whole writeup about the reason for the springs keeping the piston floating, and I suppose it makes sense. I'm not sure I got the caliper bled properly, as the bleeders seems to be plugged. I'm beginning to think they are speed bleeders, which I have never worked with.

The new radiator arrived. It looks like a pretty good piece for $233. It has fans, shroud, radiator, temp sensor and relay. I pulled out the old radiator and core support. The core support had a lot of dirt and surface rust, so I wire wheeled and painted it. Tomorrow when it's dry I'll reinstall it. After that I'm waiting on a foam seal set because all of the existing foam has turned to rock, and rubber radiator cushions, since oil and grease has semi-dissolved the existing ones. I can also wire the new fans while I wait. Once the radiator is in, that should really be the last issue, and hopefully I can actually drive this car for a bit.

I talked with my insurance lady about getting collector car insurance on it, and once that happens I'll get it titled and registered, and see how it drives.

 

when your bud timed the car, did he notice the lack of a vacuum advance can? that is the 81 comp controlled distrib that only works with the 81 e4me carb, the O2 sensor, the ecm, etc. without any one piece of that setup, none of it works correctly. you need a new 75-80 style HEI distributor. you currently have no vac or centrifugal advance. rad support. i thought that was a new one. i was gonna say that wasn't needed. old one looked solid. nice clean-up on it!

 

I've been wondering about that, since the computer has one of the connectors not hooked up. I'm primarily an LS fuel injection guy, so my only experience with distributors was years ago with air-cooled VW engines. Can this be any HEI distributor with vacuum advance? It's going on a Vortec motor, so there's nothing Corvette-specific about it. It looks like the HEI are one-wire, plus I assume a wire for the tach. I see HEIs vacuum distributors on eBay for less than $100; will those work? I suppose I can sell the current distributor on eBay to recover some of the cost.

 

Yes, that HEI unit will work. But you may have to do a lot to it to make it work well. Or it may fail right out of the box.

Folks seem to like the Davis United Ignition HEI distributors. If I hadn't found an MSD distributor on this Forum, I'd have bought one eventually. My other car has an AC Delco 93440806 distributor, which I got as a ZZ4 take-off from eBay for $100. They are stupid expensive now, and still need setup, mine needed an adjustable vacuum can, endplay shims, and new springs to set the advance correctly.

Look for a post from @lars, and email him for his timing, HEI, and Q-Jet papers. I suspect your car is in limp mode, and I'm surprised it runs at all. A proper tune, with the right parts, should really wake up your car.

 

i don't think there is that much diff between 3 to 400 DUI unit and 50 buck ebay unit. and the computer and existing distributor should be sold on ebay to somebody that is trying to run the CCC setup. (Crappy Computer Control). as soon as one input is missing from the ecm it does nothing. you have no throttle position sensor input at the ecm at the least. so park advance is defaulted to 6 or 10 degrees limp home mode.

 

Time for an update! I ordered a generic HEI distributor from eBay (or was it Amazon?) and it should be here next week. I disconnected everything from the computer and removed the computer, and the engine runs exactly the same, so obviously the computer wasn't doing anything. Once I install the new distributor I'll list the computer and old distributor on eBay. I did take a quick look at 1981 Corvette computers on eBay, and it looks like GM used the same computer in all vehicles. I assume the PROM would be burned differently for Corvette.

The new radiator/shroud/fan combo is in. It bolted in with no extra work at all. And I see the price is down to $219 on Amazon. How do they do that? I ordered the wrong rubber pads (2 5/8") but was able to reuse the old ones. I put the foam seals between the sides of the core support and radiator. I think I need an extra seal between the top of the core support and the radiator, since i don't have the stock air cleaner. I still need to put the seals on top of the core support, but am waiting until the hood is back on.

I also have to wire the radiator. It took me a while to figure it out, but I can use the wiring from the old fan. There is an ignition hot wire which I'll run to a relay to supply power to the fans, and a wire running down to a temp sensor between cylinders 6 and 8 that will ground the relay. I'll swap the temp sensor that came with the radiator into that location. I'm waiting on connectors for the fans, since they didn't come with pigtails, and some 10ga Weather Pack pins to go between the relay and the Corvette wiring. I have a 3 pin Weather Pack connector set, but the pins aren't big enough.

Still have to get the overflow fitting into the radiator fill neck, since I stripped the soft aluminum of the supplied fitting. I'll replace it with a brass one.

I've also been cleaning and painting anything that will unbolt in the engine compartment. In the words of Lucky Costa, "paint it black and put it back". And eventually I'll cut out all of the wiring for the computer controlled carburetor and distributor. Maybe even put the remaining wire into loom!

 

Looking good!

You can also use one of the plugged ports in your thermostat housing/water neck as the location for the fan switch, just check continuity to ground, or bridge the gap with a wire if the switch has a ground spade.

I'd suggest using two relays. Ideally you'd have two temp switches, too, but you can get away without that. Below is my 80s intake. Two fan relays grounded to the same switch, plus an additional temperature sensor running to an Arduino. I used the heater hose line for the sensor, which means I get temps before the thermostat opens, but I don't have heat.

I'm sure someone else will pick on you for the pressurized rubber hose and clear filter, so I won't remind you to replace that, and have a fire extinguisher ready.

 

Thanks for the input! Why two relays? The radiator manufacturer says that one relay is enough for two 12" fans, and supplies one relay with the radiator. (They call for two relays for two 16" fans.) And why two temp sensors? Do you use one per fan?

As far as the hose and filter, that replaces the glass filter that was there when I got the car. The hose is new high pressure (I forget how much) injection hose that will handle the 50 psi going to the fuel pressure regulator. I wasn't able to reuse the stock metal line when I removed the mechanical fuel pump (which didn't work with the Vortec engine). Is there a danger from the hose? I suppose I could replace the filter with a metal one, and the hose with braided line.